Equalizing mechanism for air-compressors.



No. 782,597 PATENTED FEB. 14, 1905.

. E. CHESHIRE.

EQUALIZING MEGHANISM FOR AIR OOMPRESSORS.

APPLICATION FILED APE.15.1904.

2 SHEETS -SHEET 1.

a4 a w E -l Win 6 J6 6L5 I Q In vrf0r 67% 521W W 0152070., f )QV'L/ mygPATENTED FEB. 14, 1905..

, E; CHESHIRE.

EQUALIZING MECHANISM FOR AIR GOMPRESSORS.

APPLICATION FILED APR.15.1904.

2 SHEETS-SHEET 2.

UNITED STATES Patented February 14;, I905.

PATENT OFFICE.-

EDl/VARD CHESHIRE, OF MILIVAUKEE, \VISOONSIN.

EQUALIZING MECHANISM FOR AIR-COMPRESSORS.

SPECIFICATION forming part of Letters Patent No. 782,597, dated February14, 1905,

Application filed April 15, 1904. Serial No. 203,268.

To (all whom it Duty concern:

Be it known that I, EDWARD Giiusninn, a citizen of the UnitedStatearesiding at Milwaukee, in the county of Milwaukee and State ofWisconsin, have invented a certain new and useful Improvement inEqualizing Mechanism for Air-Compressors, of which the fol lowing is afull, clear, and exact description, reference being had to theaccompanying drawings.

This invention is an improvement in doublecylinder air-compressors, andis of especial value in those double-cylinder air-compressors Whosepistons are directly connected with and driven concurrently in oppositedirections by the same crank-shaft. In the precise form in which theinvention is shown it is especially adapted to the motor air-compressorwhich is disclosed in my pending application, Serial No. 193,361. Suchmotor-driven air-conipressors have no fly-wheel, and consequently wheneach piston concludes its compressionstroke and the crank-shaft passesthe deadcenter the compressed air in the clearancespace expands and thepiston is pushed backward, so as to take up all the backlash or lostmotion with a hammer-blow. This causes objectionable noise and wear andtear.

The object of this invention is to prevent the described action and itsobjectionable results and to increase the volumetric efliciency of themachine, and these results are effected by opening up an air-passagebetween the clearance-spaces in the two cylinders just as thecrank-shaft is passing the dead center, whereby the air compressed inthe clearancespace in one cylinder will flow into the opposite cylinder,thereby equalizing the pressure against both pistons.

In the drawings, Figure 1 is a sectional plan view of a double-cylinderair-compressor equipped with my invention, said section being partly inthe plane indicated by line 1 1 of Fig. 2. Fig. 2 is a side View formost part in central vertical section in the plane indicated by line 2 2of Fig. 1. Fig. 3 is an enlargement of the rock-shaft and adjacent partsin the same plane as Fig. 1. Fig. 4 is an enlarged front view of thatpart of the mechanism which is between the two air-cylinders when thecylinder 'head plate is removed. Fig. 5 is an enlarged side elevation,partly in section, of the mechanism shown in Fig. 4.

Referring to the parts by letters, A represents the two air-compressorcylinders, which are preferably formed in a single casting.

B represents the headplate, by which both cylinders may be-closed attheir front ends.

0 U are the pistons, which are moved in reverse directions by thecrank-shaft D, to which they are connected by the connectingrods FF. Aworm-wheel I-l, attached to the crank-shaft, is turned by themotor-driven worm K, thereby turning the crank-shaft.

The above-named parts are substantially like the corresponding parts asshown and fully described in my prior application referred to.

The present invention is not, of course, limited to the specificconstruction above described; but in the specific form in which saidinvention is shown it was especially designed for use with thatparticular mechanism.

The clearancespaces mu. at the front end of the two cylinders areconnected by a port M, which, as shown, is a narrow groove milled in thefront end of the metal between the two cylinders. This groove crosses atapered valve-seat m, to which the tapered valve G is fitted. This valvenormally prevents communication between the two ends of this port M. Thevalve has an axial recess g in its front end, in which is a spring J,and this spring when the head-plate B is secured in place is compressed,so that it will hold the valve snugly against its seat. In the front endof this valve is a cross-port g, which when the valve is in the positionshown in Fig. & connects the two ends of the port M. IVhen turned intothe position indicated by the dotted lines, communication between thetwo ends of said port is effectually closed. A rockshaft E is mounted insuitable bearings substantially parallel with the axes of the cylinders.The flattened front end of this shaft enters a groove y in therear endof the valve G. On the rear end of this rock-shaft is a wheel H.

shaft tends to turn it so as to always hold said friction roller incontact with said wormwheel. On that face of the worm-wheel with whichsaid friction-roller engages are two short and rather quick cams it,located at diametrically opposite points. hen these cams engage withsaid friction-roller, they rock this rock-shaft, and thereby turn valveG, so that the cross-groove g therein connects the two ends of the portM. This engagen'ient takes place just before the crank-shaft reaches thedead-center, and thus the two cylinders are connected through the port Mand the airpressure in them is equalized while the cranl shaft ispassing said dead-center. hen the worm-wheel has turned to carry thesecams out of contact with said friction-roller, the spring N turns therock-shaft, which turns the valve (1i and closes the port connecting thetwo cylinders, this port having been open only for a very brief time, asdescribed.

As a result of the above-described construction the lost motion is takenup gradually and without substantial noise or jar. In addition, the flowof the compressed air into the suction-cylinder from the clearance-spacein the compression-cylinder increases the volumetric efficiency of thecompressor, because this transference of air takes place at about thetime when the piston in the suction-cylinder has completed itssuction-stroke. The volume of air in the suction-cylinder is thereforeincreased by the volume of air which flows into it from theclearance-space of the other cylinder. Except for this transference ofair from one cylinder to the other the air left in the clearance wouldrepresent a loss of elficiency, while with the construction described itresults in an increase of efficiency.

Substantially the same mechanism would apply to the opposite ends ofsingle-cylinder double-acting compressors.

Having described my invention, I claim 1. Inatwo-cylinderair-compressor,the co1nbination with the two cylinders,their pistons, and means for concurrently moving said pistons inopposite directions, of a port connecting the clearance-spaces in saidcylinders, a valve in said port, and means for moving said valve so asto temporarily open it just as each piston is about to terminate itscompression-stroke.

2. In a two cylinder air-compressor, the combination with the twocylinders, their pistons, and a single crank-shaft havingdiametricallydisposed crank-pins which are respectively connected withsaid pistons, of a port connecting the clearance-spaces in saidcylinders, a valve in said port, and mechanism operated by saidcrank-shaft, for operating said valve.

3. In a two-cylinder air-compressor,the combination with the twocylinders, their pistons,

and a crank-shaft having diametrically-opposed crank-pins which arerespectively connected with said pistons, of a portconnecting theclearance-spaces in said cylinders, a valve in said port, a rock-shaftoperatively engaging said valve, and cams secured to the crankshaft foroperating said rock-shaft.

4. in a two-cylinder air-compressor, the combination with the twocylinders, their pistons, and a crank-shaft having diametrically-opposederank-pins which are respectively connected with said pistons, of a portconnecting the clearance-spaces in said cylinders, an oscillating valvein said port, a rock-shaft operatively connected with said valve andhaving a crank-arm, a spring operating to turn said rock-shaft in onedirection, and a wheel secured to the crank-shaft and having twocam-surfaces engaging with said crank-arm to turn the rock-shaft in theopposite direction.

5. In a two-eylinder air-compressor, the combination with two parallelcylinders formed in the same casting, there being in themetal betweensaid cylinders a groove connecting the front open ends of saidcylinders, and there being also a conical valve-seat across said groove,a tapered valve fitted to said seat and having a transverse port and asubstantially axial recess in its front end, with a head-plate closingthe front ends of said cylinders and of said connecting groove, a rockshaft which engages with the notch in the rear end of said valve andwhich has at its opposite end a crank-arm, a spring tending to turn saidshaft in one direction, the pump-pistons, a crank shaft havingdiametrieall y opposed crank-pins which are respectively connected withsaid pistons, and a wheel secured to said crank shaft havingdiametrically opposed cams which engage with the crank-arm on therock-shaft and thereby rock it in opposition to its spring.

In testimony whereof I hereunto aiiix my signature in the presence oftwo witnesses.

EDYVA RI) CHESHIRE.

\Vitnesses:

\V. A. NUSSBAUMER, J. P. Bnusonnn.

